In general, there are three main types of metal furnace as follows. (1) direct fuel fire furnace—the furnace contains separate portions, zones or chambers for pre-heating a metal, for melting said metal, and for controlling temperature wherein the furnace utilizing the flame that is directly in contact with the metal inside the melting pot, and which is suitable for melting large number of metal; (2) indirect fuel fire furnace—the furnace having a cylindrical shape or pan shape which can be subdivided into a lift-out furnace, a tilting furnace, or a rotary crucible furnace; (3) electrical powered furnace—the furnace is subdivided into 2 types including those utilizing electrical resistance and electrical induction.
This invention can help solve the problem with the accumulation of metal oxides—such as aluminum oxides which are difficult to remove and clean up, and can have a negative effect on total yield of molten material production-inside the temperature regulating or holding portions for holding the molten metal inside the conventional direct fuel fire furnace.
A set of examples of the conventional furnace can be illustrated in FIGS. 5-8 herein a melting portion (6) is located under a pre-heating portion (5), and on one side of the furnace (6) contains a burner (9). Non-ferrous metal or aluminum can be transferred into the furnace through an opening (17) which is situated above the pre-heating portion (5) and is then heated with the burner (9) to liquefy the non-ferrous metal or aluminum into a molten material (1b). The molten material (1b) then flows over the tilted surface (15) and into the temperature regulating portion (3) wherein the temperature of said portion (3) is maintained or increased by a burner (12). The molten material (1b) shall then flow through a lower edge (13), which is an extension of a separator (10), and out of a furnace exit (4). The resulting molten material (1c) can then be used in the casting or molding process by an external casting or molding equipment. Non-ferrous material, such as aluminum, can be poured into the pre-heating portion (5) containing a lid (16) and wherein the melting portion (6) containing a door (23) attaching on one side. The door (23) can be opened for inspection and for cleaning the melting portion (6). The temperature regulating portion (3) contains a door (24) which can be opened for inspection and for cleaning of the temperature regulating portion (3).
The above components and structure of the conventional furnace have certain drawbacks since the molten material (1b) melted by a burner (9) can also flow into and mix with an oxide (21a) inside the temperature regulating portion (3) that is connected to the tilted surface (15). The molten material (1b) is then maintained at a defined temperature which is controlled by the burner (12) attaching to a ceiling lid (11). Since the molten material (1b) shall be kept under high temperature inside the temperature regulating portion (3), an oxidation reaction with the air inside the portion (3) can occur which can generate oxides (21b) that can form a cluster and grow in size inside the portion (3). Therefore, it is necessary for its users to constantly clean the temperature regulating portion (3) by opening the door (24). Nevertheless, as the cleaning process shall be conducted under high temperature, the total removal of oxides (21b) from the temperature regulating portion (3) is often a difficult and complicated task. In addition, the oxides (21b) that has not been removed and has been under high temperature for a long period of time may crystallize into corundum (Al2O3 or other forms of crystallized material, which are then intensely attached to the inner wall or surface of the furnace. The oxides (21b) as described is the root cause of the problems including, but not limited to, the shredding of said oxides (21b) from the inner furnace wall that falls into the molten material mixture, causing a hard spot in the casted or molded work and deteriorating the strength of the final product, accordingly. In addition, the oxides (21b) may grow on the inner wall of the temperature regulating portion (3), thereby, reducing the area inside the portion (3), altering or deteriorating an insulator (22) inside the temperature regulating portion (3), and subsequently, causing leakage of heat to the outside environment. To improve the quality of the product, it is therefore necessary that the furnace generates or emits the lowest amount of oxides (21b) during the production.
The problems caused by oxide accumulation as stated above had been anticipated by the U.S. Pat. No. 7,060,220 under the name “metal melting furnace” wherein the invention had intended to resolve the oxide accumulation issue by providing a separation wall between the inclined or tilted hearth linking from the melting portion to the temperature regulating portion. The separation wall creates a connecting passage that is in the level below the molten material inside the temperature regulating portion and the inclined hearth, and thereby, preventing metal oxides from flowing into the temperature regulating portion. However, said invention contains a molten metal processing portion which is less than half the size of the temperature regulating portion and has a floor level that is lower than said portion and the connecting passage which may increase complexity of the system due to the increase in number of furnace components. A Japanese patent JP2006071266 under the name “metal melting furnace” had also described a portion separator with additional heating plate within the melting portion. Reduction of oxide had also been anticipated by two other patent applications: one by a Japanese patent application JP2001272171A under the name “tower type aluminium melting and holding furnace” by increasing the temperature of melting portion and temperature regulating portion; another by a US patent application US20150042024 under the name “metal melting furnace” by utilizing a charging port, an upper air vent and a heating plate on the ground inside the melting portion, and a burner head is located on the side of the temperature regulating portion. The applications as suggest, however, had utilized a set of complex components which may not be suitable in some circumstances.
The above prior arts were intended to improve the components or structures of furnace or to provide the means to control the amount of gases or chemical processes in order to reduce the amount of iron oxide generation in the system. However, there is still lack of invention in the prior arts that has the capability to improve efficiency of the industrious, non-ferrous metal furnace, such as aluminium furnace, in eliminating oxide from furnace without introducing complex components such as heating plates, doors, or separators, in the furnace system.